1. Field of the Invention
The invention is based on a fuel injector.
2. Description of the Prior Art
A fuel injector with an integrated pressure booster is known for instance from German Patent Disclosure DE 103 35 340 A1. The pressure booster has a pressure booster piston, guided in a housing of the fuel injector, that acts on a compression chamber, a differential pressure chamber, and a high-pressure chamber. With a first control valve, a rear control chamber of a nozzle needle is triggered, and the control volume is diverted into a low-pressure/return flow system. A second control valve connects the differential pressure chamber of the pressure booster with the low-pressure/return flow system as well. As a result of the change of pressure in the differential pressure chamber, the pressure booster piston presses into the compression chamber and compresses the fuel there, which as a result experiences a pressure increase that is transmitted to a pressure shoulder of the nozzle needle, so that the high pressure acting on the pressure shoulder lifts a nozzle needle from the nozzle needle seat and injects the fuel, at the fuel pressure elevated above the system pressure, into the combustion chamber of an internal combustion engine.
In German Patent Application DE 100 206 038 840.2, it is shown to provide one return flow connection each, for communication with the low-pressure/return flow system, for both the first control valve that triggers the nozzle needle and the second control valve that triggers the pressure booster.
Since the return flow systems for the first control valve of the nozzle needle and for the second control valve of the pressure booster are exposed to different pressure levels, and furthermore the return flow system of the pressure booster is subjected to severe pressure surges, a technologically appropriate decoupling of the two return flow circuits inside the fuel injector is necessary. In addition, a suitable disposition of the two return flow connections on the injector housing is necessary.